Cartridge filters are just that - a pool filter with one or more cartridges inside. The cartridge filter is good and can filter down to 10 microns in some cases. Not quite as good as D.E. but overall there isn't a dramatic water clarity difference.
A Cartridge Filter is an excellent choice for any size pool and in fact, they make cartridge filters as small as 20 sq ft up to 500 sq ft. They are excellent at filtering the water and will filter down to as low as 15-20 microns. Cartridge filters are a cloth-like material and the dirt, algae, and particles will stick to the cartridge and allow clean water to flow through. Much like any cartridge filter that you use for water purification.
The benefit of a cartridge filter is that they are easy to clean. Simply remove the cartridge and hose it off. The downside of this is that you cannot backwash a Cartridge Filter so when it gets dirty you need to take it apart and clean it. So figure that depending on the size of the Cartridge Filter you will be taking it apart and cleaning it every month to every 4-6 months.
I suggest going with a larger Cartridge Filter on your pool to save time in between cleaning and to provide the best water quality. So for a 15,000-gallon pool, I suggest a 300 sq ft filter, for a 20,000-gallon pool a 400 sq ft filter and for a 30,000-gallon pool a 500 sq ft filter. You can use a smaller filter if you choose, just note that you will be cleaning it often and the water flow may not be as efficient as going with a larger filter.
* Filters down to 15-20 Microns – great
* Easy to clean and maintain
* Very large filtration sq. ft available
* Parts are long lasting
* Water clarity is great
* Need to clean more often than D.E. filters
* Doesn't filter down to D.E. filter levels
* Must install the correct size for best results